GIGANTIC FOSSIL AMMONITE OF FERNIE

Titanites occidentalis, Fernie Ammonite

The Fernie ammonite, Titanites occidentalis, from outcrops on Coal Mountain near Fernie, British Columbia, Canada. 

This beauty is the remains of a carnivorous cephalopod within the family Dorsoplanitidae that lived and died in a shallow sea some 150 million years ago.

If you would like to get off the beaten track and hike up to see this ancient beauty, you will want to head to the town of Fernie in British Columbia close to the Alberta border. 

This is the traditional territory of the the Yaq̓it ʔa·knuqⱡi ‘it First Nation who have lived here since time immemorial. There was some active logging along the hillside in 2021, so if you are looking at older directions on how to get to the site be mindful that many of the trailheads have been altered and a fair bit of bushwhacking will be necessary to get to the fossil site proper. That being said, the loggers from CanWel may have clear-cut large sections of the hillside but they did give the ammonite a wide berth and have left it intact.

Wildsight, a non-profit environmental group out of the Kimberly Cranbrook area has been trying to gain grant funding to open up the site as an educational hike with educational signage for folks visiting the Fernie area. It is likely the province of British Columbia would top up those funds if they are able to place the ammonite under the Heritage Conservation Act. CanWel would remain the owners of the land but the province could assume the liability for those visiting this iconic piece of British Columbia's palaeontological history. 

Driving to the trail base is along an easy access road just east of town along Fernie Coal Road. There are some nice exposures of Cretaceous plant material on the north side (left-hand side) of the road as you head from Fernie towards Coal Creek. I recently drove up to Fernie to look at Cretaceous plant material and locate the access point to the now infamous Late Jurassic (Tithonian) Titanites (S.S. Buckman, 1921) site. While the drive out of town is on an easy, well-maintained road, the slog up to the ammonite site is often a wet, steep push.

Fernie, British Columbia, Canada

The first Titanites occidentalis was about one-third the size and was incorrectly identified as Lytoceras, a fast-moving nektonic carnivore. The specimen you see here is significantly larger at 1.4 metres (about four and a half feet) and rare in North America. 

Titanites occidentalis, the Western Giant, is the second known specimen of this extinct fossil species. 

The first was discovered in 1947 in nearby Coal Creek by a British Columbia Geophysical Society mapping team. When they first discovered this marine fossil high up on the hillside, they could not believe their eyes — both because it is clearly marine at the top of a mountain and the sheer size of this ancient beauty.

In the summer of 1947, a field crew was mapping coal outcrops for the BC Geological Survey east of Fernie. One of the students reported finding “a fossil truck tire.” Fair enough. The similarity of size and optics are pretty close to your average Goodridge. 

A few years later, GSC Paleontologist Hans Frebold described and named the fossil Titanites occidentalis after the large Jurassic ammonites from Dorset, England. The name comes from Greek mythology. Tithonus, as you may recall, was the Prince of Troy. He fell in love with Eos, the Greek Goddess of the Dawn. Eos begged Zeus to make her mortal lover immortal. Zeus granted her wish but did not grant Tithonus eternal youth. He did indeed live forever — ageing hideously. Ah, Zeus, you old trickster. It is a clever play on time placement. Dawn is the beginning of the day and the Tithonian being the latest age of the Late Jurassic. Clever Hans!

HIKING TO THE FERNIE AMMONITE

From the town of Fernie, British Columbia, head east along Coal Creek Road towards Coal Creek. The site is 3.81 km from the base of Coal Creek Road to the trailhead as the crow flies. I have mapped it here for you in yellow and added the wee purple GPS marker for the ammonite site proper. There is a nice, dark grey to black roadcut exposure of Cretaceous plants on the north side of the dirt road that is your cue to pull over and park.  

You access what is left of the trailhead on the south side of the road. You will need to cross the creek to begin your ascent. There is no easy way across the creek and you'll want to tackle this one with a friend when the water level is low. 

The beginning of the trail is not clear but a bit of searching will reveal the trailhead with its telltale signs of previous hikers. This is a moderate 6.3-kilometre hike up & back bushwhacking through scrub and fallen trees. Heading up, you will make about a 246-metre elevation gain. You will likely not have a cellular signal up here but if you download the Google Map to your mobile, you will have GPS to guide you. The area has been recently logged so much of the original trail has been destroyed. There may now be easier vehicle access up the logging roads but I have not driven them since the logging and new road construction.

If you are coming in from out of town, the closest airport is Cranbrook. Then it is about an hour and change to Fernie and another 15-minutes or so to park near the site.

You will want to leave your hammers with your vehicle (no need to carry the weight and this lovely should never be struck with anything more than a raindrop) as this site is best enjoyed with a camera. 

This is a site you will want to wear hiking boots to access. Know that these will get wet as you cross the creek. 

If you would like to see the ammonite but are not keen on the hike, a cast has been made by fossil preparator Rod Bartlett is on display at the Courtenay Museum in Courtenay, Vancouver Island, Canada. 

Respect for the Land / Leave No Trace

As your feet move up the hillside, you can imagine this land 10,000 years ago, rising above great glaciers. Where footfalls trace the steps of those that came before you. This land has been home to the Yaq̓it ʔa·knuqⱡi ‘it First Nation and Ktunaxa or Kukin ʔamakis First Nations whose oral history have them living here since time immemorial. Like them, take only what you need and no more than the land offers — packing out anything that you packed in. 

Fernie Ammonite Palaeo Coordinates: 49°29'04"N 115°00'49"W

HETEROPTERA: SNEAKOPTERA

A sweet little water bug from the suborder Heteroptera (Latreille, 1810). He looks more like a cartoon character that any other specimen I've seen. 

This fun fellow is in the collections of Tim Dingman. The deeply awesome Jim Barkley gets credit for this charming photo. The cartoon effect comes from this guy missing his abdomen. He hails from Eocene deposits of the Green River Formation of Western Colorado.

The Green River Formation is an Eocene geologic formation that records a 12 million year history of sedimentation in a group of intermountain lakes in three basins along the present-day Green River in Colorado, Wyoming, and Utah. It is one of the most important outcrops we have for insight into life in the Eocene. It gives a window into what our world looked like about 50 million years ago. 

The first documented records of invertebrate fossils from what is now called the Green River Formation are in the journals of early missionaries and explorers such as S. A. Parker, 1840, and J. C. Fremont, 1845. Geologist Dr. John Evans collected the first fossil fish, described as Culpea humilis — later renamed Knightia eocaena — from the Green River beds in 1856.

Edward Drinker Cope collected extensively from the area and produced several publications on the fossil fish from 1870 onwards. Ferdinand Vandeveer Hayden, geologist-in-charge of the United States Geological and Geographical Survey of the Territories, the forerunner of the United States Geological Survey,  first used the name "Green River Shales" for the fossil sites in 1869.

Millions of fish fossils have been collected from the area, commercial collectors operating from legal quarries on state and private land have been responsible for the majority of Green River vertebrate fossils in public and private collections all over the world.

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HUMPBACK WHALES: MEGAPTERA NOVAENGLIAE

Look deep into the knowing eye of this magnificent one. He is a Humpback whale, Megaptera novaeangliae, a species of baleen whale for whom I hold a special place in my heart. 

Baleens are toothless whales who feed on plankton and other wee oceanic tasties that they consume through their baleens, a specialised filter of flexible keratin plates that frame their mouth and fit within their robust jaws.

Baleen whales, the mysticetes, split from toothed whales, the Odontoceti, around 34 million years ago. The split allowed our toothless friends to enjoy a new feeding niche and make their way in a sea with limited food resources. There are fifteen species of baleen whales who inhabit all major oceans. Their number include our humbacks, grays, right whales and the massive blue whale. Their territory runs as a wide band running from the Antarctic ice edge to 81°N latitude. These filter feeders

In the Kwak̓wala language of the Kwakiutl or Kwakwaka'wakw, speakers of Kwak'wala, of the Pacific Northwest, and my cousins on my father's side, whales are known as g̱wa̱'ya̱m. Both the California grey and the Humpback whale live on the coast. Only a small number of individuals in First Nation society had the right to harpoon a whale. This is a practice from many years ago. It was generally only the Chief who was bestowed this great honour. Humpback whales like to feed close to shore and enter the local inlets. Around Vancouver Island and along the coast of British Columbia, this made them a welcome food source as the long days of winter passed into Spring.

Humpback whales are rorquals, members of the Balaenopteridae family that includes the blue, fin, Bryde's, sei and minke whales. The rorquals are believed to have diverged from the other families of the suborder Mysticeti during the middle Miocene. 

While cetaceans were historically thought to have descended from mesonychids—which would place them outside the order Artiodactyla—molecular evidence supports them as a clade of even-toed ungulates—our dear Artiodactyla. 

It is one of the larger rorqual species, with adults ranging in length from 12–16 m (39–52 ft) and weighing around 25–30 metric tons (28–33 short tons). The humpback has a distinctive body shape, with long pectoral fins and a knobbly head. It is known for breaching and other distinctive surface behaviours, making it popular with whale watchers and the lucky few who see them from the decks of our local ferries.

Both male and female humpback whales vocalize, but only males produce the long, loud, complex "song" for which the species is famous. Males produce a complex soulful song lasting 10 to 20 minutes, which they repeat for hours at a time. I imagine Gregorian Monks vocalizing their chant with each individual melody strengthening and complimenting that of their peers. All the males in a group produce the same song, which differed in each season. Its purpose is not clear, though it may help induce estrus in females and bonding amongst the males.

Humpback Whale, Megaptera novaeangliae

Found in oceans and seas around the world, humpback whales typically migrate up to 25,000 km (16,000 mi) each year. 

They feed in polar waters and migrate to tropical or subtropical waters to breed and give birth, fasting and living off their fat reserves. Their diet consists mostly of krill and small fish. 

Humpbacks have a diverse repertoire of feeding methods, including the bubble net technique.

Humpbacks are a friendly species that interact with other cetaceans such as bottlenose dolphins. They are also friendly and oddly protective of humans. You may recall hearing about an incident off the Cook Islands a few years back. Nan Hauser was snorkelling and ran into a tiger shark. Two adult humpback whales rushed to her aid, blocking the shark from reaching her and pushing her back towards the shore. We could learn a thing or two from their kindness. We have not been as good to them as they have been to us.

Like other large whales, the humpback was a tasty and profitable target for the whaling industry. My grandfather and uncle participated in that industry out of Coal Harbour on northern Vancouver Island back in the 1950s. So did many of my First Nation cousins. My cousin John Lyon has told me tales of those days and the slippery stench of that work.

Six whaling stations operated on the coast of British Columbia between 1905 and 1976. Two of these stations were located at Haida Gwaii, one at Rose Harbour and the other at Naden Harbour. Over 9,400 large whales were taken from the waters around Haida Gwaii. The catch included blue whales, fin whales, sei whales, humpback whales, sperm whales and right whales. In the early years of the century, primarily humpback whales were taken. In later years, fin whales and sperm whales dominated the catch. 

Whales were hunted off South Moresby in Haida Gwaii, on the north side of Holberg Inlet in the Quatsino Sound region. It was the norm at the time and a way to make a living, especially for those who had hoped to work in the local coal mine but lost their employment when it shut down. 

While my First Nations relatives hunted whales in small numbers and many years ago, my Norwegian relatives participated in the hunt on a scale that nearly led to their extinction before the process was banned. The Coal Harbour Whaling Station closed in 1967. Once it had closed, my grandfather Einar Eikanger, my mother's father, took to fishing and my uncle Harry lost his life the year before when he slipped and fell over the side of the boat. He was crushed between the hull and a Humpback in rough seas. 

Humpback populations have partially recovered since that time to build their population up to 80,000 animals worldwide—but entanglement in fishing gear, collisions with ships, and noise pollution continue to negatively impact the species. So be kind if you see them. Turn your engine off and see if you can hear their soulful cries echoing in the water.

I did up a video on Humpback Whales over on YouTube so you could see them in all their majesty. Here is the link: https://youtu.be/_Vbta7kQNoM

NEVADA PALAEONTOLOGY: BERLIN-ICHTHYOSAUR STATE PARK

Time Slows at Berlin-Ichthyosaur State Park

High on the hillside up a long entry road sits the entrance to Berlin-Ichthyosaur State Park in central Nevada.

A worn American flag and sun bleached outbuildings greet you on your way to the outcrops. Away from the hustle and bustle that define the rest of Nevada this place feels remarkably serene. Your eyes squint against the sun as you search for ammonoids and other marine fossil fauna while your nose tends to the assault from the bracing smell of sage brush.

This site holds many stories. The interpretive centre displays wonderful marine reptiles, ichthyosaurs in situ, as you might expect from the name of the park — but it also showcases years of history lovingly tended. This stretch of dry golden low hills dappled with the yellow of creosote and desert grasses is an important locality for our understanding of the Carnian-Norian boundary (CNB) in North America.

The area is known worldwide as one of the most important ichthyosaur Fossil-Lagerstätte because of the sheer volume of remarkably well-preserved, fully articulated (all the sweet bones laid out all in a row...) specimens of Shonisaurus popularis.

Rich ammonoid faunas outcrop in the barren hills of the Upper Triassic (Early Norian, Kerri zone), Luning Formation, West Union Canyon, Nevada. They were studied by N. J. Silberling (1959) and provide support for the definition of the Schucherti and Macrolobatus zones of the latest Carnian — which are here overlain by well-preserved faunas of the earliest Norian Kerri Zone. 

The genus Gonionotites, very common in the Tethys and British Columbia, is for the moment, unknown in Nevada. The Upper Carnian faunas are dominated by Tropitidae, while Juvavitidae are conspicuously lacking. 

Middle Triassic Ammonoids

Despite its importance, no further investigations had been done at this site for a good 50 years. That changed in 2010 when Jim Haggart, Mike Orchard and Paul Smith — all local Vancouverites — collaborated on a project that took them down to Nevada to look at the conodonts and ammonoids. They did a bed-by-bed sampling of ammonoids and conodonts in West Union Canyon during October of that year.

October is an ideal time to do fieldwork in this area. There are a few good weeks between screaming hot and frigid cold. It is also tarantula breeding season so keep your eyes peeled. Those sweet little burrows you see are not from rodents but rather largish arachnids. 

The eastern side of the canyon provides the best record of the Macrolobatus Zone, which is represented by several beds yielding ammonoids of the Tropites group, together with Anatropites div. sp. 

Conodont faunas from both these and higher beds are dominated by ornate metapolygnthids that would formerly have been collectively referred to Metapolygnathus primitius, a species long known to straddle the CNB. Within this lower part of the section, they resemble forms that have been separated as Metapolygnathus mersinensis. Slightly higher, forms close to Epigondolella' orchardi and a single Orchardella n. sp. occur. This association can be correlated with the latest Carnian in British Columbia.

Higher in the section, the ammonoid fauna shows a sudden change and is dominated by Tropithisbites. Few tens of metres above, but slightly below the first occurrence of Norian ammonoids Guembelites jandianus and Stikinoceras, two new species of conodonts (Gen et sp. nov. A and B) appear that also occur close to the favoured Carnian/Norian boundary at Black Bear Ridge, British Columbia. Stratigraphically higher collections continue to be dominated by forms close to M. mersinensis and E. orchardi after BC's own Mike Orchard.

The best exposure of the Kerri Zone is on the western side of the West Union Canyon. Ammonoids, dominated by Guembelites and Stikinoceras div. sp., have been collected from several fossil-bearing levels. Conodont faunas replicate those of the east section. The collected ammonoids fit perfectly well with the faunas described by Silberling in 1959, but they differ somewhat from coeval faunas of the Tethys and Canada. 

The ammonoid fauna paints a compelling picture of Tethyan influence with a series of smoking guns. We see an abundance of Tropitidae in the Carnian, a lack of Pterosirenites in the Norian, copious Guembelites, the Tethyan species G. philostrati, the stratigraphic position of G. clavatus and the rare occurrence of Gonionotites. Their hallelujah moment was likely finding an undescribed species of the thin-shelled bivalve Halobia similar to Halobia beyrichi — the clincher that perhaps seals this deal on Tethyan influence. 

I'll take a boo to see what Christopher McRoberts published on the find. A jolly good idea to have him on this expedition as it would have been easy to overlook if the focus remained solely on the conodonts and ammonoids. McRoberts has published on the much-studied Pardonet Formation up in the Willison Lake Area of Northeastern, British Columbia. He knows a thing or two about Upper Triassic Bivalvia and the correlation to coeval faunas elsewhere in the North American Cordillera, and to the Boreal, Panthalassan and Tethyan faunal realms. 

If you fancy a read, they published a paper: "Towards the definition of the Carnian/Norian Boundary: New data on Ammonoids and Conodonts from central Nevada," which you can find in the proceedings of the 21st Canadian Paleontology Conference; by Haggart, J W (ed.); Smith, P L (ed.); Canadian Paleontology Conference Proceedings no. 9, 2011 p. 9-10.

Fig. 1. Location map of Berlin-Ichthyosaur State Park

Marco Balini, James Jenks, Riccardo Martin, Christopher McRoberts, along with Mike Orchard and Norman Siberling, did a bed by bed sampling in 2013 and published on The Carnian/Norian boundary succession at Berlin-Ichthyosaur State Park (Upper Triassic, central Nevada, USA) and published in January 2014 in Paläontologische Zeitschrift 89:399–433. That work is available for download from ResearchGate. The original is in German, but there is a translation available.

After years of reading about the correlation between British Columbia and Nevada, I had the very great pleasure of walking through these same sections in October 2019 with members of the Vancouver Paleontological Society and Vancouver Island Palaeontological Society. It was with that same crew that I'd originally explored fossil sites in the Canadian Rockies in the early 2000s. Those early trips led to paper after paper and the exciting revelations that inspired our Nevada adventure.

If you plan your own adventure, you'll want to keep an eye out for some of the other modern fauna — mountain lions, snakes, lizards, scorpions, wolves, coyotes, foxes, ground squirrels, rabbits, falcons, hawks, eagles, bobcats, sheep, deer and pronghorns.

Figure One: Location map of Berlin-Ichthyosaur State Park. A detailed road log with access information for this locality is provided in Lucas et al. (2007).

UNESCOCERATOPS: A SMALL LEPTOCERATOPSID DINOSAUR

Unescoceratops koppelhusae, Julius Csotonyi

A very sweet small leptoceratopsid dinosaur, Unescoceratops koppelhusae — a new species in the collections of the Royal Tyrrell Museum of Palaeontology in Drumheller, Alberta.

The colourful and beautifully detailed painting you see here is by the very talented Julius Csotonyi who captured the magnificence of form, texture and palette to bring this small leptoceratopsid dinosaur to life.

The Royal Tyrrell Museum of Palaeontology, named in honour of Joseph Burr Tyrrell, is a palaeontology museum and research facility in Drumheller, Alberta, Canada. 

This jaw is the holotype specimen of this small leptoceratopsid dinosaur. Only a handful of isolated fossils have been found from this species, including a jaw that is the holotype specimen now in collections at the Royal Tyrell. 

The Royal Tyrrell Museum of Palaeontology, named in honour of Joseph Burr Tyrrell, is a palaeontology museum and research facility in Drumheller, Alberta, Canada. 

Unescoceratops koppelhusae, RTMP Collections

The rusty chocolate jaw bone you see here is the puzzle piece that helped all of the research come together and help us to better understand more about the diminutive leptoceratopsid dinosaurs from Alberta. 

The Cleveland Museum of Natural History's Michael Ryan and David Evans of the Royal Ontario Museum in Toronto recently determined that the specimen was a new genus and species. 

Unescoceratops is a genus of leptoceratopsid ceratopsian dinosaurs known from the Late Cretaceous (about 76.5-75 million years ago) of Alberta, Canada. Unescoceratops is thought to have been between one and two meters long and less than 91 kilograms. A plant-eater, its teeth were the roundest of all Leptocertopsids.

Dinosaur Provincial Park, Alberta, Canada

The genus name acknowledges the UNESCO  World Heritage Site, Dinosaur Provincial Park, where the fossil was found. 

In addition to its particularly beautiful scenery, Dinosaur Provincial Park – located at the heart of the province of Alberta's badlands – is unmatched in terms of the number and variety of high-quality specimens.

To date, they represent more than 44 species, 34 genera and 10 families of dinosaurs, dating back 75-77 million years. This provides us with remarkable insight into life millions of years ago.

The park contains exceptional riparian habitat features as well as badlands of outstanding aesthetic value.

The creamy honey, beige and rust coloured hills around the fossil locality are outstanding examples of major geological processes and fluvial erosion patterns in semi-arid steppes — think glorious! 

The scenic badlands stretch along 26 kilometres of high quality and virtually undisturbed riparian habitat, presenting a landscape of stark but exceptional natural beauty.

The species name honours Dr. Eva Koppelhus, who has made significant contributions to vertebrate palaeontology and palynology. 

The genus is named to honour the UNESCO World Heritage Site designation for the locality where the specimen was found and from the Greek “ceratops,” which means 'horned face'. 

Dr Michael Ryan explained that he meant to honour UNESCO's efforts to increase understanding of natural history sites around the world.

© Julius T. Csotonyi An illustration of Unescoceratops koppelhusae, a plant-eating dinosaur from the Late Cretaceous period that lived approximately 75 million years ago shared with his gracious permission. 

ABOUT THE ARTIST

Dr. Julius Csotonyi is a Vancouver-based scientific illustrator and natural history fine artist. He is a featured paleoartist on Season One of BC's Fossil Bounty. Julius has a scientific background in ecology (MSc) and microbiology (PhD) which has taken him to study sensitive ecosystems, from sand dunes in the Rocky Mountain parks to hydrothermal vents at the bottom of the Pacific Ocean. 

These experiences have fuelled his strong resolve to work toward preserving our Earth’s biota. Painting biological subjects is one means that he uses to both enhance public awareness of biological diversity and to motivate concern for its welfare.   

He paints murals and panels that have appeared in numerous museums including the Smithsonian’s National Museum of Natural History, press release images for scientific publications, books, stamp sets — including the outstanding 2018 “Sharks of Canada” set for Canada Post — and coins for the Royal Canadian Mint. To view more of Julius Csotonyi's exquisite work visit: https://csotonyi.com/

AMMONITE TIME KEEPERS

Argonauticeras besairei, José Juárez Ruiz

An exceptional example of the fractal building of an ammonite septum, in this clytoceratid Argonauticeras besairei from the awesome José Juárez Ruiz.

Ammonites were predatory, squidlike creatures that lived inside coil-shaped shells.

Like other cephalopods, ammonites had sharp, beak-like jaws inside a ring of squid-like tentacles that extended from their shells. 

They used these tentacles to snare prey, — plankton, vegetation, fish and crustaceans — similar to the way a squid or octopus hunt today.

Catching a fish with your hands is no easy feat, as I am sure you know. But the Ammonites were skilled and successful hunters. They caught their prey while swimming and floating in the water column. 

Within their shells, they had a number of chambers, called septa, filled with gas or fluid that were interconnected by a wee air tube. By pushing air in or out, they were able to control their buoyancy in the water column.

They lived in the last chamber of their shells, continuously building new shell material as they grew. As each new chamber was added, the squid-like body of the ammonite would move down to occupy the final outside chamber.

They were a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. 

These molluscs, commonly referred to as ammonites, are more closely related to living coleoids — octopuses, squid, and cuttlefish) than they are to shelled nautiloids such as the living Nautilus species.

The Ammonoidea can be divided into six orders:

• Agoniatitida, Lower Devonian - Middle Devonian
• Clymeniida, Upper Devonian
• Goniatitida, Middle Devonian - Upper Permian
• Prolecanitida, Upper Devonian - Upper Triassic
• Ceratitida, Upper Permian - Upper Triassic
• Ammonitida, Lower Jurassic - Upper Cretaceous

Ammonites have intricate and complex patterns on their shells called sutures. The suture patterns differ across species and tell us what time period the ammonite is from. If they are geometric with numerous undivided lobes and saddles and eight lobes around the conch, we refer to their pattern as goniatitic, a characteristic of Paleozoic ammonites.

If they are ceratitic with lobes that have subdivided tips; giving them a saw-toothed appearance and rounded undivided saddles, they are likely Triassic. For some lovely Triassic ammonites, take a look at the specimens that come out of Hallstatt, Austria and from the outcrops in the Humboldt Mountains of Nevada.

Hoplites bennettiana (Sowby, 1826) Christophe Marot

If they have lobes and saddles that are fluted, with rounded subdivisions instead of saw-toothed, they are likely Jurassic or Cretaceous. If you'd like to see a particularly beautiful Lower Jurassic ammonite, take a peek at Apodoceras. Wonderful ridging in that species.

One of my favourite Cretaceous ammonites is the ammonite, Hoplites bennettiana (Sowby, 1826). This beauty is from Albian deposits near Carrière de Courcelles, Villemoyenne, near la région de Troyes (Aube) Champagne in northeastern France.

At the time that this fellow was swimming in our oceans, ankylosaurs were strolling about Mongolia and stomping through the foliage in Utah, Kansas and Texas. Bony fish were swimming over what would become the strata making up Canada, the Czech Republic and Australia. Cartilaginous fish were prowling the western interior seaway of North America and a strange extinct herbivorous mammal, Eobaatar, was snuffling through Mongolia, Spain and England.

In some classifications, these are left as suborders, included in only three orders: Goniatitida, Ceratitida, and Ammonitida. Once you get to know them, ammonites in their various shapes and suturing patterns make it much easier to date an ammonite and the rock formation where it is found.

Ammonites first appeared about 240 million years ago, though they descended from straight-shelled cephalopods called bacrites that date back to the Devonian, about 415 million years ago, and the last species vanished in the Cretaceous–Paleogene extinction event.

They were prolific breeders that evolved rapidly. If you could cast a fishing line into our ancient seas, it is likely that you would hook an ammonite, not a fish. They were prolific back in the day, living (and sometimes dying) in schools in oceans around the globe. We find ammonite fossils (and plenty of them) in sedimentary rock from all over the world.

In some cases, we find rock beds where we can see evidence of a new species that evolved, lived and died out in such a short time span that we can walk through time, following the course of evolution using ammonites as a window into the past.

For this reason, they make excellent index fossils. An index fossil is a species that allows us to link a particular rock formation, layered in time with a particular species or genus found there. 

Generally, deeper is older, so we use the sedimentary layers of rock to match up to specific geologic time periods, rather like the way we use tree rings to date trees. A handy way to compare fossils and date strata across the globe.

References: Inoue, S., Kondo, S. Suture pattern formation in ammonites and the unknown rear mantle structure. Sci Rep 6, 33689 (2016). https://doi.org/10.1038/srep33689

https://www.nature.com/articles/srep33689?fbclid=IwAR1BhBrDqhv8LDjqF60EXdfLR7wPE4zDivwGORTUEgCd2GghD5W7KOfg6Co#citeas

Photos: Argonauticeras besairei from the awesome José Juárez Ruiz.

Photo: Hoplites bennettiana from near Troyes, France. Collection de Christophe Marot